If a rock is thrown upward on the planet Mars with a velocity of 11 m/s, its height above the ground (in meters) after t seconds is given by H = 11t - 1.86t. (a) Find the velocity (in m/s) of the rock after 1 second. 7.28 m/s (b) Find the velocity (in m/s) of the rock when t = a. 3.72 m/s x (c) When (in seconds) will the rock hit the surface? (Round your answer to one decimal place.) t=5.91 S (d) With what velocity (in m/s) will the rock hit the surface? 4.08 x m/s